Research Of Catalytic Degradation Of T700 Carbon Fiber Epoxy Resin Composites And Application Of Recycled Carbon Fiber

Carbon fiber reinforced resin matrix composites are widely used in aerospace,marine vessels,automobile manufacturing,sports equipment and many other fields due to their excellent mechanical properties and light weight and high strength.With the extensive use of carbon fiber composites,carbon fiber composite waste has also increased.The subsequent treatment of these wastes has become an urgent problem to be solved.Therefore,the researchers hope to degrade the resin matrix in the composite and recover the carbon fiber with higher value.The epoxy resin is generally used as the matrix of the carbon fiber reinforced plastic,which is the thermosetting resin that could forms an insoluble and infusible three-dimensional network structure after curing and crosslinking reaction,and the chemical property of epoxy 1s relatively stable,which makes the degradation process become difficult.At present,the existing methods of degradation and recovery have their shortcomings.In this experiment,a series of studies on the catalytic degradation of resin matrix and the recovery and reuse of carbon fiber in composite materials were carried out.After the T700 carbon fiber reinforced TGDDM/DDS composite prepared,the composite was immersed in molten KCl/Z1nCl2 at 350?.After 90 min of reaction time,the resin matrix was completely degraded and the carbon fibers in the composite were recovered.During the degradation of the resin matrix,the empty electron orbital on the Zn2+ ion in the molten salt complexed with the lone pair of electrons on the nitrogen atom in the resin matrix,causing the shared electron pair of the nitrogen atom and the adjacent carbon to shift and the energy of the carbon-nitrogen bond to be weaken,that reduced the reaction temperature and shortened the reaction time.The recovered carbon fiber surface contained a small amount of residual carbon,which can be removed at 500?for 10 min with the catalysis of TiO2,and the carbon fibers were well protected.Compared with commercial carbon fiber,the recycled carbon fiber surface had a reduced oxygen content and was slightly inert;the graphitization structure was almost unchanged;and the tensile strength of recycled carbon fiber reached 4702.3 MPa,which retained 95.7%of that of the commercial carbon fiber.In addition,the composite was immersed in a solution of Zn3(PO4)2/H3PO4 at 250?.After 60 min of reaction time,the resin matrix was completely degraded.The degradation mechanism of the resin was similar to that of the molten salt method.The recovered carbon fiber surface was clean and had no resin matrix residue;the surface element composition and graphitization structure of the recycled fiber were similar to those of commercial carbon fiber;the tensile strength of recycled carbon fiber reached 4521.2 MPa,which was 92.0%of that of the commercial carbon fiber.Based on the recycling research,a series of investigations on the application of recycled carbon fiber were carried out.The unidirectional DGEB A epoxy resin composite was prepared by using the recycled carbon fiber after sizing treatment,and the flexture strength and flexture modulus of the obtained composite material were close to those of the commercial carbon fiber reinforced sample,and the recycled T700 carbon fiber/DGEBA epoxy composite has a retention rate of more than 85%in ILSS.In the experiment of recovering carbon fiber reinforcing thermoplastic resin,it was found that the chopped recycled carbon fiber had a good reinforcing effect on the PP and PA6 resin,and the obtained composite materials had high tensile,flexture and impact properties.The processing properties and thermal stability of the composites had nearly no effect,and the crystallinity of the resin matrix slightly changed depending on the carbon fibers to be added.